The correct answer is option 'B' - insensitive towards.

Explanation:

Understanding the context:
In the given sentence, the couple is described as "wicked." This implies that they are cruel, evil, or immoral in their behavior. The sentence also mentions their behavior towards the dog. To determine the correct answer, we need to analyze the possible meanings of each option and choose the one that best fits the context.

Explanation of the options:
a) Revengeful: This means seeking revenge or desiring to cause harm to someone in response to a perceived wrong. While the wicked couple may indeed be seeking revenge, the sentence does not provide any evidence of this. Therefore, this option is unlikely to be correct.
b) Insensitive towards: This means lacking sensitivity or concern for the feelings or needs of others. Given that the wicked couple is described as such, it is plausible that they are also insensitive towards the dog. This option aligns well with the context and is the correct answer.
c) Hitting at: This phrase typically suggests attempting to criticize or harm someone indirectly. However, the sentence does not provide any evidence of the couple hitting at the dog. Therefore, this option is unlikely to be correct.
d) Jealous of: This means feeling resentful or envious of someone else's possessions, qualities, or achievements. While the couple may indeed be jealous of the dog, the sentence does not provide any evidence of this. Therefore, this option is unlikely to be correct.

Conclusion:
Based on the context of the sentence, the correct answer is option 'B' - insensitive towards. This option aligns well with the description of the wicked couple's behavior and their treatment of the dog.